Many different methods for the preparation of alkylene oxides have been developed. One such method involves the epoxidation of an olefin in a liquid phase reaction using an organic hydroperoxide as the oxidizing agent. NL-C-1010372 describes a process comprising reacting propene with ethylbenzene hydroperoxide to obtain propylene oxide and 1-phenyl ethanol. The 1-phenyl ethanol is subsequently dehydrated to obtain styrene, which is a useful starting material for other chemical reactions.
WO01/70714, assigned to Sumitomo, describes a process relating to oxidizing isopropylbenzene (also known as “cumene”) to obtain isopropylbenzene peroxide as an oxygen carrier for the epoxidation of propylene to produce propylene oxide and isopropylbenzene alcohol (cumyl alcohol). The isopropylphenyl alcohol is dehydrated/hydrogenated, via a hydrogenolysis step, to isopropylbenzene (cumene) and recycled for repeated use without the co-production of styrene. During the hydrogenolysis step, substantial quantities of i-propylcyclohexane and cumene dimer are produced as undesirable by-products, due to the hydrogenation or dimerization of cumene and alpha-methyl styrene which remain on the hydrogenation bed after being produced.
U.S. Pat. No. 6,455,712, assigned to Shell, describes a process for producing alkylene oxide (also known as oxirane) compounds, such as propylene oxide, by oxidizing olefin with alkylbenzene hydroperoxide obtained by oxidizing alkylbenzene with oxygen. The alkylbenzene hydroperoxide is converted to alkylphenyl alcohol which is dehydrated and hydrogenated, followed by fractionation, to separate alkylbenzene from other side products for reuse for making alkylbenzene hydroperoxide. Substantial quantities of alkylphenyl alcohol could be converted to alkylcyclohexane and/or dimers/oligomers of alkylbenzene as side products.
It is therefore desirable to develop a more efficient process which would combine multiple process steps for converting alkylphenyl alcohol to alkylbenzene and fractionation into fewer steps and yet accumulate fewer undesirable side products of alkylbenzene, such as dimers/oligomers and alkylcyclohexane, to minimize loss of alkylbenzene utilized.